Yamanashi Prefecture doesn’t have an ocean. However, local specialties like awabi-no-nigai (boiled abalone) and the high consumption of marine products show that it has strong ties to the sea through its food culture. In this article, I would like to introduce marine education activities in Yamanashi Prefecture where you can inspect the characteristic five-sided symmetry of echinoderms with your own hands. It all begins with the question: What part of sea urchins is used for topping sushi?